THE STUDENT PLT STATED THAT HE DEPARTED MCKINNEY MUNICIPAL ARPT AT APRX 1030 LCL EN ROUTE TO WICHITA FALLS, TX. HE SAID HE BECAME DISORIENTED WHILE EN ROUTE, BUT LANDED AT WICHITA FALLS AT APRX 1220 LCL. THE PLT DID NOT REFUEL THE ACFT. HE THEN DEPARTED WICHITA FALLS AT APRX 1240 LCL FOR THE RETURN FLT TO MCKINNEY. THE PLT BECAME DISORIENTED DURING THE FLT. FUEL EXHAUSTION OCCURRED AND THE PLT ELECTED TO LAND IN A FLD NEAR ALVORD, TX. HE AND A FARMER WENT TO DECATUR MUNICIPALARPT, BOUGHT 10 GALLONS OF FUEL AND FUELED THE ACFT. THE PLT TOOK OFF FROM THE FLD WITH THE INTENTION OF FLYING TO DECATUR MUNICIPAL TO TOP OFF THE TANKS. HE BECAME DISORIENTED ONCE AGAIN ON THE WAY TO DECATUR AND CONTACTED ADDISON TOWER FOR ASSISTANCE. WHILE BEING VECTORED, FUEL EXHAUSTION OCCURRED ONCE AGAIN. THE ACFT NOSED OVER IN A FIELD DURING THE FORCED LANDING.